You absolutely could not get it done quicker or with less effort using SDL2. 2D games are deceptively complex beyond trivial examples, and most of your effort would be wasted on poor and ad-hoc reimplemetation of features that an engine already takes care of. If you want to finish a game, use an engine. If you can't finish a game with an engine, you'll never finish one without an engine, because without an engine it's exponentially more difficult.
And the premise that a project within an engine is a "bespoke and unmaintainable hindrance" as opposed to a pile of raw AI generated code is simply laughable. If you're going to use Copilot anyway, why not also use an engine? It's obvious at that point you care less about code and code quality than getting a product finished as quickly as possible.
I don't know, I managed to complete a few games, one with SDL2 and a few with libgdx. But could never complete anything with a "GUI engine" (don't know what the terminology is) like Godot or Unity.
When everything is code, it "makes sense". You have a main loop, you can reason about what is happening when. You can set a breakpoint and walk through everything step by step.
I have no idea what's going on in Unity or Godot. Everything is completely unfamiliar, there are a bunch of abstractions I'm unfamiliar with and I can't rely on any of my past experience. I'm basically starting from scratch.
If I was tasked with making a game quickly, I could probably do it faster in SDL or Libgdx (if that's still around) than I could learn unity or Godot.
Yes, you do have to actually learn how to use an engine, just as you had to learn how to use SDL or any other library. Most people, once they learn how to use such engines, are far more productive than people writing entirely low-level code. You can have a basic 2D or 3D scene ready in Godot in minutes, with collision detection, lighting, camera and a controllable player. from scratch, the equivalent of either might take days or weeks.
I'm not disparaging low-level coding here, I write projects in C, LuaJIT and SDL myself. But I know from personal experience how liberating it can be to not have to deal with 90% of what amounts to uninteresting boilerplate and focus on the actual creative part of a project.
Your comment reminds me of when I participated in a game jam one time irl. A lot of other people were using existing engines and there were some pretty cool results that different groups had.
I worked alone and used SDL. This was also one of my first attempts at making a game.
I managed to make a couple of command line inputs and outputs in the terminal, and then use SDL to render a single sprite on screen that did not move or anything. Needless to say, my entry did not win any prices :p
And the premise that a project within an engine is a "bespoke and unmaintainable hindrance" as opposed to a pile of raw AI generated code is simply laughable. If you're going to use Copilot anyway, why not also use an engine? It's obvious at that point you care less about code and code quality than getting a product finished as quickly as possible.